The line emission mapper x-ray microcalorimeter instrument requires a 4 K cryogenic system to precool a continuous adiabatic demagnetization refrigerator enabling high-resolution x-ray spectroscopy. The cryogenic system described in this work provides the required structural and thermal environments using mature cooling and structural technologies. The system is comprised of a dewar design based on heritage manufacturing processes and an efficient four-stage pulse tube cryocooler with supporting control electronics.